diff --git a/notes-on-testing.md b/notes-on-testing.md
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@@ -2,4 +2,8 @@
 - test Mailbox screens on different screen types/sizes/ratios
 - according to the mattermost discussion of 13/14 dec, there may be variations of illustration size used on mailbox screens - normal, short and none... if that decision is made, then that will need to be tested too
 
+- discussion on the MM 20/12 - error handling.  Find out how to trigger each error response mentioned, to vrify that they are handled correctly.
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 [Back to Testing](https://code.briarproject.org/briar/briar/-/wikis/testing)
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